Various industries involve systems for dispensing material, such as dry solids, onto conveying devices. In the hydrocarbon exploration and production industries, for example, materials are often dispensed from storage units onto conveyor belts for delivery to another location or system. One exemplary scenario often utilizing material storage units and conveyors is a hydraulic fracturing well site requiring the use of proppant or sand. In many frac job sites, a material storage unit, such as the Frac Sander by National Oilwell Varco, Inc, is used to dispense the sand or proppant onto a conveyor for delivery to another component, such as a blender.
Presently known systems and techniques for delivering materials via conveying devices may have one or more drawbacks. For example, as illustrated in FIG. 1, the material 32 often overflows off the sides of the conveyor 40 as it is being discharged from the dispensing unit 30. Depending upon the particular application, material overflow can freeze the conveyor belt from moving, make it difficult or impossible to determine or control the rate of discharge of material from the conveyor to the desired destination or cause other unwanted consequences.
For another example, various existing systems and techniques that attempt to determine or control the amount of material being discharged from the conveyor to the blender, or other destination, may have one or more drawbacks. Some systems attempt to determine the amount of material discharged by calculating the loss of weight of the entire material storage unit after material is dispensed onto the conveyor. Depending upon the application, such techniques may be cumbersome, inaccurate or cause other undesirable consequences. Other techniques involve running the conveyor very fast and frequently varying the open position of the discharge gates on the material dispenser, which are believed to often be inaccurate, cumbersome or cause other undesirable consequences. Yet other techniques require a first person at the equipment site to operate the gate controls and a second person, also at the equipment site near the end of the conveyor. The second person watches the discharge of material from the conveyor belt to the blender (or other destination), and signals the first person to move the discharge gates to vary the supply of material onto the conveyor. This technique may also be inaccurate, cumbersome and cause other unwanted consequences.
It should be understood that the above-described discussion is provided for illustrative purposes only and is not intended to limit the scope or subject matter of the appended claims or those of any related patent application or patent. Thus, none of the appended claims or claims of any related application or patent should be limited by the above discussion or construed to address, include or exclude each or any of the cited examples, features and/or disadvantages, merely because of the mention thereof herein.
Accordingly, there exists a need for improved systems, apparatus and methods useful to assist in controlling the amount or rate of delivery of material onto or off of a conveyor having one or more of the attributes or capabilities described or shown in, or as may be apparent from, the other portions of this patent.